[clang] [clang] [Static analyzer]: add initial support for builtin overflow (PR #102602)

[Balazs Benics via cfe-commits]

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@@ -21,16 +21,67 @@
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicExtent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
 
 using namespace clang;
 using namespace ento;
 
 namespace {
 
+QualType getOverflowBuiltinResultType(const CallEvent &Call) {
+  assert(Call.getNumArgs() == 3);
+
+  return Call.getArgExpr(2)->getType()->getPointeeType();
+}
+
+QualType getOverflowBuiltinResultType(const CallEvent &Call, CheckerContext &C,
+                                      unsigned BI) {
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steakhal wrote:

Have you considered using `cast<FunctionDecl>(Call.getDecl())->getParamDecl(2)->getType()` as a type?

Is it because its not always present in the declaration of the builting? `__builtin_mul_overflow`
In that case you could take the `Call.getArgExpr(2)->getType()->getPointeeType()` I think.

https://github.com/llvm/llvm-project/pull/102602